double (de)clutching.... what exactly is this?
Discussion
pimpin gimp said:
I've heard the term many times but have no idea what it means, could anyone enlighten me please?
Double declutching is done on a down change, this is an example.1. You are driving along at 50mph in top gear, gentle on the throttle.
2. Lift off the throttle.
3. Dip the clutch.
4. Move the gear lever into neutral.
5. Lift off the clutch.
6. Blip the throttle taking the revs up by about 1000rpm more than they were in the previous gear (this may vary experiment with it).
7. Get off the throttle.
8. Dip the clutch and select forth gear.
9. Lift off the clutch.
10. Put your foot on the throttle.
Practice this until you get it right, If you can do a good double declutch a single declutch will be a doddle.
Yung Man said:
Double declutching is done on a down change, this is an example.
1. You are driving along at 50mph in top gear, gentle on the throttle.
2. Lift off the throttle.
3. Dip the clutch.
4. Move the gear lever into neutral.
5. Lift off the clutch.
6. Blip the throttle taking the revs up by about 1000rpm more than they were in the previous gear (this may vary experiment with it).
7. Get off the throttle.
8. Dip the clutch and select forth gear.
9. Lift off the clutch.
10. Put your foot on the throttle.
Practice this until you get it right, If you can do a good double declutch a single declutch will be a doddle.
And up-change too, sans blip1. You are driving along at 50mph in top gear, gentle on the throttle.
2. Lift off the throttle.
3. Dip the clutch.
4. Move the gear lever into neutral.
5. Lift off the clutch.
6. Blip the throttle taking the revs up by about 1000rpm more than they were in the previous gear (this may vary experiment with it).
7. Get off the throttle.
8. Dip the clutch and select forth gear.
9. Lift off the clutch.
10. Put your foot on the throttle.
Practice this until you get it right, If you can do a good double declutch a single declutch will be a doddle.
BertBert said:
Yung Man said:
Double declutching is done on a down change, this is an example.
1. You are driving along at 50mph in top gear, gentle on the throttle.
2. Lift off the throttle.
3. Dip the clutch.
4. Move the gear lever into neutral.
5. Lift off the clutch.
6. Blip the throttle taking the revs up by about 1000rpm more than they were in the previous gear (this may vary experiment with it).
7. Get off the throttle.
8. Dip the clutch and select forth gear.
9. Lift off the clutch.
10. Put your foot on the throttle.
Practice this until you get it right, If you can do a good double declutch a single declutch will be a doddle.
And up-change too, sans blip1. You are driving along at 50mph in top gear, gentle on the throttle.
2. Lift off the throttle.
3. Dip the clutch.
4. Move the gear lever into neutral.
5. Lift off the clutch.
6. Blip the throttle taking the revs up by about 1000rpm more than they were in the previous gear (this may vary experiment with it).
7. Get off the throttle.
8. Dip the clutch and select forth gear.
9. Lift off the clutch.
10. Put your foot on the throttle.
Practice this until you get it right, If you can do a good double declutch a single declutch will be a doddle.
In general DDC always was less necessary on upchanges than on downchanges, and of course the need for the latter is now largely confined to very old classic or vintage vehicles.
Best wishes all,
Dave.
TripleS said:
Quite right. My FiL, sadly no longer with us, used to be a bus driver in the 1950s, and he explained to me about doing DDC upchanges on the buses then in service.
In general DDC always was less necessary on upchanges than on downchanges, and of course the need for the latter is now largely confined to very old classic or vintage vehicles.
Best wishes all,
Dave.
A old friend of mine who drove buses, coaches and HGVs for a living, described the DDC for the upchange in the 'olden days'...where you took it out of gear, let the clutch up, walked to the back of the bus and back, put the clutch down and selected the next higher gear!In general DDC always was less necessary on upchanges than on downchanges, and of course the need for the latter is now largely confined to very old classic or vintage vehicles.
Best wishes all,
Dave.
Bert
BertBert said:
TripleS said:
Quite right. My FiL, sadly no longer with us, used to be a bus driver in the 1950s, and he explained to me about doing DDC upchanges on the buses then in service.
In general DDC always was less necessary on upchanges than on downchanges, and of course the need for the latter is now largely confined to very old classic or vintage vehicles.
Best wishes all,
Dave.
A old friend of mine who drove buses, coaches and HGVs for a living, described the DDC for the upchange in the 'olden days'...where you took it out of gear, let the clutch up, walked to the back of the bus and back, put the clutch down and selected the next higher gear!In general DDC always was less necessary on upchanges than on downchanges, and of course the need for the latter is now largely confined to very old classic or vintage vehicles.
Best wishes all,
Dave.
Bert
Oh that's a further development of the technique then. Mind you, I can envisage that leading to other problems.Best wishes all,
Dave.
Did anyone here explain why (you DDC)?
The reason is that with old gearboxes pre-synchromesh or Hewland-type race boxes, again no synchromesh, with the lever in neutral and the clutch up, a throttle blip would spin the layshaft up to more or less the speed of the lower gear.
So you wouldn't knock large chunks of the dog teeth as you force it through, or make nasty crashing noises on down changes. Or miss it altogether.
The other by-product to this blipping part of the process is that you'd also speed the engine up, so when you did lift the clutch in the lower gear, it would be somewhere matched to the road speed, thus avoiding the third of the unwanted side effects - a chirrup from the tyres and risk of locked driving wheels and a passenger about to give out with a technicolour yawn.
So get your dancing shoes on and practise ddc with toe & heeling, in the wet or looking for a lap record.
The reason is that with old gearboxes pre-synchromesh or Hewland-type race boxes, again no synchromesh, with the lever in neutral and the clutch up, a throttle blip would spin the layshaft up to more or less the speed of the lower gear.
So you wouldn't knock large chunks of the dog teeth as you force it through, or make nasty crashing noises on down changes. Or miss it altogether.
The other by-product to this blipping part of the process is that you'd also speed the engine up, so when you did lift the clutch in the lower gear, it would be somewhere matched to the road speed, thus avoiding the third of the unwanted side effects - a chirrup from the tyres and risk of locked driving wheels and a passenger about to give out with a technicolour yawn.
So get your dancing shoes on and practise ddc with toe & heeling, in the wet or looking for a lap record.
ph123 said:
Did anyone here explain why (you DDC)?
The reason is that with old gearboxes pre-synchromesh or Hewland-type race boxes, again no synchromesh, with the lever in neutral and the clutch up, a throttle blip would spin the layshaft up to more or less the speed of the lower gear.
So you wouldn't knock large chunks of the dog teeth as you force it through, or make nasty crashing noises on down changes. Or miss it altogether.
The other by-product to this blipping part of the process is that you'd also speed the engine up, so when you did lift the clutch in the lower gear, it would be somewhere matched to the road speed, thus avoiding the third of the unwanted side effects - a chirrup from the tyres and risk of locked driving wheels and a passenger about to give out with a technicolour yawn.
So get your dancing shoes on and practise ddc with toe & heeling, in the wet or looking for a lap record.
yep, I think we have done the "why" to death here!The reason is that with old gearboxes pre-synchromesh or Hewland-type race boxes, again no synchromesh, with the lever in neutral and the clutch up, a throttle blip would spin the layshaft up to more or less the speed of the lower gear.
So you wouldn't knock large chunks of the dog teeth as you force it through, or make nasty crashing noises on down changes. Or miss it altogether.
The other by-product to this blipping part of the process is that you'd also speed the engine up, so when you did lift the clutch in the lower gear, it would be somewhere matched to the road speed, thus avoiding the third of the unwanted side effects - a chirrup from the tyres and risk of locked driving wheels and a passenger about to give out with a technicolour yawn.
So get your dancing shoes on and practise ddc with toe & heeling, in the wet or looking for a lap record.
Bert
BertBert said:
Yung Man said:
Double declutching is done on a down change, this is an example.
1. You are driving along at 50mph in top gear, gentle on the throttle.
2. Lift off the throttle.
3. Dip the clutch.
4. Move the gear lever into neutral.
5. Lift off the clutch.
6. Blip the throttle taking the revs up by about 1000rpm more than they were in the previous gear (this may vary experiment with it).
7. Get off the throttle.
8. Dip the clutch and select forth gear.
9. Lift off the clutch.
10. Put your foot on the throttle.
Practice this until you get it right, If you can do a good double declutch a single declutch will be a doddle.
And up-change too, sans blip1. You are driving along at 50mph in top gear, gentle on the throttle.
2. Lift off the throttle.
3. Dip the clutch.
4. Move the gear lever into neutral.
5. Lift off the clutch.
6. Blip the throttle taking the revs up by about 1000rpm more than they were in the previous gear (this may vary experiment with it).
7. Get off the throttle.
8. Dip the clutch and select forth gear.
9. Lift off the clutch.
10. Put your foot on the throttle.
Practice this until you get it right, If you can do a good double declutch a single declutch will be a doddle.
7db said:
BertBert said:
Yung Man said:
Double declutching is done on a down change, this is an example.
1. You are driving along at 50mph in top gear, gentle on the throttle.
2. Lift off the throttle.
3. Dip the clutch.
4. Move the gear lever into neutral.
5. Lift off the clutch.
6. Blip the throttle taking the revs up by about 1000rpm more than they were in the previous gear (this may vary experiment with it).
7. Get off the throttle.
8. Dip the clutch and select forth gear.
9. Lift off the clutch.
10. Put your foot on the throttle.
Practice this until you get it right, If you can do a good double declutch a single declutch will be a doddle.
And up-change too, sans blip1. You are driving along at 50mph in top gear, gentle on the throttle.
2. Lift off the throttle.
3. Dip the clutch.
4. Move the gear lever into neutral.
5. Lift off the clutch.
6. Blip the throttle taking the revs up by about 1000rpm more than they were in the previous gear (this may vary experiment with it).
7. Get off the throttle.
8. Dip the clutch and select forth gear.
9. Lift off the clutch.
10. Put your foot on the throttle.
Practice this until you get it right, If you can do a good double declutch a single declutch will be a doddle.
Best wishes all,
Dave.
7db said:
Or let the revs die off and blip them back up again.
If that's on an up-change (engione revs dropping during the change) then doesn't imply that you've performed the gear change to slowly relative to the responsiveness of the engine? It would imo be better to either change gear quicker so that you catch the engine revs as they reach the right point or (if you're already changing gear as quickly as you can / want to) slow the engine response down by keeping the throttle slightly open.TripleS said:
In general DDC always was less necessary on upchanges than on downchanges, and of course the need for the latter is now largely confined to very old classic or vintage vehicles.
Best wishes all,
Dave.
I would disagree. Using a DDC on, for instance, an approach to a hazard, say a roundabout, allows the engine revs to stay higher and more in the power band. It would be , therefor, more responsive when accelerating through the hazard.( I am talking an empty(ish) road and making progress scenario here.)Best wishes all,
Dave.
The other time it is invaluable is on snow and ice, the gearchange, especially when slowing down or climbing a hill, is much smoother and, if done correctly, will help stop wheelspin/sliding.
I am an old fart, who learned to drive on armoured vehicles with pre-select gearboxes and this was the method(strictly, a variation of DDC) taught.
Smoothness is everything, especially in the wet, or mud or ice & snow. It is also used by many motorcyclists, particularly when slowing/coming to a halt as it keeps things smooth and the revs up, nearer the power band(if done & timed correctly) Just another view
Cheers
Tony
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